Light Emitting Unit and Display Device

ABSTRACT

A light emitting unit and a display device is disclosed, wherein the display device includes: a light emitting unit, including: a first semiconductor layer; an active layer disposed on the first semiconductor layer; a second semiconductor layer disposed on the active layer; and a first protecting layer disposed on the second semiconductor layer, wherein the first protecting layer includes oxygen, nitrogen, and at least one element selected from the group consisting of Al, Ga, In, and Si.

BACKGROUND 1. Field

The present disclosure relates to a light emitting unit and a displaydevice using the same.

2. Description of Related Art

With the continuous advancement of technologies related to displays, allthe display apparatuses are now developed toward compactness, thinness,and lightness. Applications of thin displays are numerous. Mostelectronic products for daily use, such as mobile phones, notebookcomputers, video cameras, still cameras, music displays, mobilenavigators, and TV sets, employ such display panels.

Herein, one kind of the light source used in the display device can be alight emitting diode. Even though the development of the light emittingdiode is getting matured, many manufacturers are desired to provide alight emitting diode with improved chip reliability or enhanced lightextraction efficiency.

Therefore, it is desirable to provide a light emitting unit and adisplay device using the same, which has improved chip reliability orenhanced light extraction efficiency.

SUMMARY

The present disclosure provides a display device, which comprises: alight emitting unit, comprising: a first semiconductor layer; an activelayer disposed on the first semiconductor layer; a second semiconductorlayer disposed on the active layer; and a first protecting layerdisposed on the second semiconductor layer, wherein the first protectinglayer comprises oxygen, nitrogen, and at least one element selected fromthe group consisting of Al, Ga, In, and Si.

The present disclosure also provides a light emitting unit, whichcomprises: a first semiconductor layer; an active layer disposed on thefirst semiconductor layer; a second semiconductor layer disposed on theactive layer; and a first protecting layer disposed on the secondsemiconductor layer, wherein the first protecting layer comprisesoxygen, nitrogen, and at least one element selected from the groupconsisting of Al, Ga, In, and Si.

Other novel features of the disclosure will become more apparent fromthe following detailed description when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a light emitting unit according toEmbodiment 1 of the present disclosure.

FIG. 2A is a diagram showing nitrogen and oxygen atomic percentages in asecond semiconductor layer and a first protecting layer of a lightemitting unit according to Embodiment 1 of the present disclosure.

FIG. 2B is an enlarged view of a region R1 indicated in FIG. 1 accordingto another embodiment of the present disclosure.

FIG. 2C is an enlarged view of a region R2 indicated in FIG. 1 accordingto another embodiment of the present disclosure.

FIG. 3 is a cross-sectional view of a light emitting unit according toEmbodiment 2 of the present disclosure.

FIG. 4 is a cross-sectional view of a light emitting unit according toEmbodiment 3 of the present disclosure.

FIG. 5 is a cross-sectional view of a light emitting unit according toEmbodiment 4 of the present disclosure.

FIG. 6 is a cross-sectional view of a light emitting unit according toEmbodiment 5 of the present disclosure.

FIG. 7 is a cross-sectional view of a display device according toEmbodiment 6 of the present disclosure.

FIG. 8 is a cross-sectional view of a display device according toEmbodiment 7 of the present disclosure.

FIG. 9 is a cross-sectional view of a light emitting unit according toEmbodiment 8 of the present disclosure.

FIG. 10 is a cross-sectional view of a light emitting unit according toEmbodiment 9 of the present disclosure.

FIG. 11 is a cross-sectional view of a light emitting unit according toEmbodiment 10 of the present disclosure.

FIG. 12 is a cross-sectional view of a light emitting unit according toEmbodiment 11 of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENT

The following embodiments when read with the accompanying drawings aremade to clearly exhibit the above-mentioned and other technicalcontents, features and/or effects of the present disclosure. Through theexposition by means of the specific embodiments, people would furtherunderstand the technical means and effects the present disclosure adoptsto achieve the above-indicated objectives. Moreover, as the contentsdisclosed herein should be readily understood and can be implemented bya person skilled in the art, all equivalent changes or modificationswhich do not depart from the concept of the present disclosure should beencompassed by the appended claims.

Furthermore, the ordinals recited in the specification and the claimssuch as “first”, “second” and so on are intended only to describe theelements claimed and imply or represent neither that the claimedelements have any proceeding ordinals, nor that sequence between oneclaimed element and another claimed element or between steps of amanufacturing method. The use of these ordinals is merely todifferentiate one claimed element having a certain designation fromanother claimed element having the same designation.

Furthermore, the ordinals recited in the specification and the claimssuch as “above”, “over”, or “on” are intended not only directly contactwith the other element, but also intended indirectly contact with theother element. Similarly, the ordinals recited in the specification andthe claims such as “below”, or “under” are intended not only directlycontact with the other element but also intended indirectly contact withthe other element.

In addition, the features in different embodiments of the presentdisclosure can be mixed to form another embodiment.

Embodiment 1

FIG. 1 is a cross-sectional view of a light emitting unit of the presentembodiment. The light emitting unit of the present embodiment comprises:a first semiconductor layer 11; an active layer 12 disposed on the firstsemiconductor layer 11; a second semiconductor layer 13 disposed on theactive layer 12; and a first protecting layer 14 disposed on the secondsemiconductor layer 13, wherein the first protecting layer 14 comprisesoxygen, nitrogen, and at least one element selected from the groupconsisting of Al, Ga, In, and Si.

The light emitting unit of the present embodiment may be a lightemitting diode. The size of the light emitting unit could be ranged from0.1 μm to 100 μm, which is called a micro-LED; or ranged from 100 μm to300 μm, which is called a mini-LED; or above 300 μm, which is called anormal LED. The active layer 12 of the light emitting unit play as aquantum well layer, the material of the active layer 12 could be organicmaterial or inorganic material, and the active layer 12 may have quantumdot material. The material of the first semiconductor layer 11 could beP-type semiconductor or N-type semiconductor, the material of the secondsemiconductor layer 13 could be N-type semiconductor or P-typesemiconductor, and the material of the second semiconductor layer 13 isopposite to the material of the first semiconductor layer 11 (P-N pair).

Since the second semiconductor layer 13 may be easily damaged, the firstprotecting layer 14 is disposed on the second semiconductor layer 13 toprevent the damage of the second semiconductor layer 13; thus thereliability of the light emitting unit can further be improved. Inaddition, the light emitting unit of the present embodiment is atop-emission light emitting unit. While the first protecting layer 14 isdisposed between the second semiconductor layer 13 and a layer (notshown in the figure), the refractive index of the first protecting layer14 is between the refractive index of the second semiconductor layer 13and the refractive index of the layer to reduce total reflectionoccurred.

Herein, the dominant material of the first semiconductor layer 11, theactive layer 12 and the second semiconductor layer 13 can be GaN orother semiconductor material suitable for a light emitting diode. Inconsideration of the lattice match between the second semiconductorlayer 13 and the first protecting layer 14, the material for the firstprotecting layer 14 may comprise oxygen, nitrogen, and at least oneelement selected from the group consisting of Al, Ga, In, and Si.

In one aspect, the material of the second semiconductor layer 13 is GaN,and the material of the first protecting layer 14 is GaO_(x)N_(y). Therefractive index of GaN is 2.5, and the refractive index of GaO_(x)N_(y)is between 1.8 and 2.5. Hence, the refractive index difference betweenthe second semiconductor layer 13 and the first protecting layer 14 islowered than the refractive index difference between the secondsemiconductor layer 13 and the layer (not shown in the figure) above thefirst protecting layer 14 and the second semiconductor layer 13, andthus the total reflections can be reduced.

FIG. 2A is a diagram showing nitrogen and oxygen atomic percentages inthe second semiconductor layer 13 and the first protecting layer 14 of alight emitting unit. As shown in FIG. 1 and FIG. 2A, in the presentembodiment, the second semiconductor layer 13 and the first protectinglayer 14 can be differentiated via the following measurement procedure.Herein, the atomic percentages in the second semiconductor layer 13 andthe first protecting layer 14 can be examined via Energy dispersivespectroscopy (EDX), Secondary-ion mass spectrometry (SIMS), X-rayphotoelectron spectroscopy (XPS) or other suitable equipment. In thepresent disclosure, an element content means an atomic percentage (at %)or a ratio of a target element atomic to whole measuring elements'atomics at a measuring region or a measuring point. For example, anitrogen content or a nitrogen atomic percentage means a percentage or aratio of nitrogen atomic to whole measuring elements' atomics at ameasuring region or a measuring point.

First, nitrogen content at the center C of the second semiconductorlayer 13 is measured, and the obtained nitrogen content at the center Cis defined as 100%. Next, a point with a nitrogen content being 90%based on the obtained nitrogen content at the center C is defined. Then,the oxygen content at this point is measured. It can be found that bothoxygen and nitrogen are present at this point located in the firstprotecting layer 14

As shown in FIG. 2A, close to the second semiconductor layer 13, thefirst protecting layer 14 has a first oxygen atomic percentage and afirst nitrogen atomic percentage, and the first oxygen atomic percentageis less than the first nitrogen atomic percentage.

In addition, as shown in FIG. 1, the first protecting layer 14 has afirst top surface 141, which is a rough surface. Herein, after formingthe first protecting layer 14, an imprinting process or other patterningprocess is performed on the first protecting layer 14 to form the roughsurface. When the first top surface 141 of the first protecting layer 14is a rough surface, the light extraction or uniformity of the lightemitting unit can further be increased.

In addition, the first semiconductor layer 11 has a second top surface111. The first top surface 141 has a first roughness, the second topsurface 111 has a second roughness, and the first roughness is greaterthan the second roughness. Herein, the first roughness of the first topsurface 141 and the second roughness of the second top surface 111 canbe examined from SEM cross-section image.

In the aspect shown in FIG. 1, the first top surface 141 is a roughsurface with plural uniform arc shapes. However, the present disclosureis not limited thereto.

For example, FIG. 2B is an enlarged view of a region R1 indicated inFIG. 1 according to another embodiment of the present disclosure. Inthis embodiment, the first top surface 141 is not a uniform roughsurface. In addition, FIG. 2C is an enlarged view of a region R2indicated in FIG. 1 according to another embodiment of the presentdisclosure, and the second top surface 111 is also not a uniform roughsurface. When the first top surface 141 and the second top surface 111are not uniform rough surfaces, the first roughness and the secondroughness can be defined as follow. First, the region R1 with a width W1ranged from 3 μm to 30 μm and the region R2 with a width W2 ranged from3 μm to 30 μm are examined. Top 5 high peaks and top 5 low peaks can berespectively found in the region R1 and the region R2. The heightdifference between the third high peak and the third low peak in theregion R1 is defined as the first roughness, and the height differencebetween the third high peak and the third low peak in the region R2 isdefined as the second roughness.

As shown in FIG. 1, to form the electrodes of the light emitting unit, avia hole 17 is firstly formed through a lithography process. Next, apassivation layer 18 is formed on the first semiconductor layer 11 andin the via hole 17. The material for the passivation layer 18 can be,for example, a silicon oxide, a silicon oxynitride, a silicon nitride,aluminum oxide, resin, polymer, photoresist, or a combination thereof,but the present disclosure is not limited thereto. Then, a first contactelectrode 151 and a second contact electrode 161 are formed on the sameside of the first semiconductor layer 11 and in the via hole 17 by ametalorganic chemical vapor deposition (MOCVD), physical vapordeposition (PVD) process, electroplating process, or other thin filmdeposition process, but the present disclosure is not limited thereto.Herein, the material for the first contact electrode 151 and the secondcontact electrode 161 can respectively a reflective electrode material,such as Ag, Al, Ni, Cr, Cu, Au, Pd, Pt, Sn, W, Rh, Jr, Ru, Mg, Zn, or analloy thereof, but the present disclosure is not limited thereto.Finally, a first electrode 15 and a second electrode 16 are formed onthe first contact electrode 151 and the second contact electrode 161 bythe MOCVD, the PVD, the electro plating process, or other depositionprocess, but the present disclosure is not limited thereto. Herein, thematerial for the first electrode 15 and the second electrode 16 can be,for example, Ag, Al, Ni, Cr, Cu, Au, Pd, Pt, or an alloy thereof, butthe present disclosure is not limited thereto.

Hence, the light emitting unit of the present embodiment furthercomprises a first electrode 15 and a second electrode 16 disposed at thesame side of the light emitting unit, the first electrode 15electrically connects to the second semiconductor layer 13, and thesecond electrode 16 electrically connects to the first semiconductorlayer 11. In addition, the second electrode 16 is disposed below thefirst semiconductor layer 11, the first electrode 15 is disposed belowthe first semiconductor layer 11, and a via hole 17 penetrates throughthe first semiconductor layer 11 and the active layer 12, and at least apart of the first electrode disposed in the via hole 17. A part of thevia hole 17 is further extended into the second semiconductor 13, and apart of the first electrode 15 is further embedded into the secondsemiconductor layer 13.

In the present embodiment, the via hole 17 is firstly formed through alithography process, which required high accuracy. However, when thefirst electrode 15 is formed in the via hole 17 to electrically connectto the second semiconductor layer 13, the area for forming the firstelectrode 15 can be reduced, all the area except the region with the viahole 17 can emit light, and therefore the area capable of emitting lightcan be increased.

Furthermore, the light emitting unit further comprises a passivationlayer 18, the passivation layer 18 is disposed between the firstelectrode 15 in the via hole 17 and the first semiconductor layer 11,and the passivation layer 18 could be also disposed on a side wall 171of the via hole 17.

In the present embodiment, the light emitting unit further comprises afirst contact electrode 151 and a second contact electrode 161, whichcan facilitate the formation of the first electrode 15 and the secondelectrode 16. However, in another embodiment of the present disclosure,the light emitting unit does not comprise the aforesaid first contactelectrode 151 and the second contact electrode 161.

In addition, the light emitting unit further comprises a firstencapsulating layer 19, the first encapsulating layer 19 is around apart of the first electrode 15 and a part of the second electrode 16 andis disposed on a side wall 112 of the first semiconductor layer 11, aside wall 121 of the active layer 12 and a side wall 131 of the secondsemiconductor layer 13. Herein, the material for the first encapsulatinglayer 19 can be silicon oxide, silicon nitride, silicon oxynitride,aluminum oxide, resin, polymer, photoresist, other non-sulfur inorganicor organic encapsulating material, or a combination thereof.

Embodiment 2

FIG. 3 is a cross-sectional view of a light emitting unit of the presentembodiment. The light emitting unit of the present embodiment is similarto that shown in Embodiment 1, except that the first electrode 15 is notembedded into the second semiconductor layer 13. More specifically, thefirst electrode 15 contacts a bottom surface 132 of the secondsemiconductor layer 13.

Embodiment 3

FIG. 4 is a cross-sectional view of a light emitting unit of the presentembodiment. The light emitting unit of the present embodiment is similarto that shown in. Embodiment 1, except the following differences.

In the present embodiment, a mesa process is performed to form a cavity133 near to the first semiconductor layer 11 and the active layer 12.Next, a first electrode 15 is formed in the cavity 133 and a secondelectrode 16 is formed on the first semiconductor layer 11. Then, afirst encapsulating layer 19 is formed, wherein the first encapsulatinglayer 19 is around a part of the first electrode 15 and a part of thesecond electrode 16 and is disposed on a side wall 112 of the firstsemiconductor layer 11, a side wall 121 of the active layer 12 and aside wall 131 of the second semiconductor layer 13. The firstencapsulating layer 19 may be disposed in a part of the cavity 133.

The process for forming the light emitting unit of Embodiment 1 is morecomplex than the process of the present embodiment. However, since thearea of first semiconductor layer 11 and the active layer 12 on thesecond semiconductor layer 13 is decreased in the present embodiment,the area capable of emitting light in the light emitting unit of thepresent embodiment is less than the area capable of emitting light inEmbodiment 1.

Embodiment 4

FIG. 5 is a cross-sectional view of a light emitting unit of the presentembodiment. The light emitting unit of the present embodiment is similarto that shown in Embodiment 1, except the following difference.

In the present embodiment, the light emitting unit further comprises asecond protecting layer 21 disposed on the first protecting layer 14,wherein the first protecting layer 14 has a first top surface 141, thesecond protecting layer 21 has a third top surface 211, the first topsurface 141 has a first roughness, the third top surface 211 has a thirdroughness, and the first roughness is greater than the third roughness.In another embodiment of the present disclosure, the third top surface211 is not a uniform rough surface; in this case, the third roughnesscan be defined by the same method shown in FIG. 2B and FIG. 2C.

Herein, the material for the second protecting layer 21 can be, forexample, silicon oxide, silicon nitride, silicon oxynitride, aluminumoxide, resin, polymer, photoresist, or a combination thereof, but thepresent disclosure is not limited thereto.

In one aspect of the present disclosure, when the second protectinglayer 21 is an oxide film, the second protecting layer 21 has a secondoxygen atomic percentage, and the first oxygen atomic percentage of thefirst protecting layer 14 is less than the second oxygen atomicpercentage of the second protecting layer 21.

In another aspect of the present disclosure, when the second protectinglayer 21 is a nitride film, the second protecting layer 21 has a secondnitrogen atomic percentage, and the first nitrogen atomic percentage ofthe first protecting layer 14 is less than the second nitrogen atomicpercentage of the second protecting layer 21.

Embodiment 5

FIG. 6 is a cross-sectional view of a light emitting unit of the presentembodiment. The light emitting unit of the present embodiment is similarto that shown in Embodiment 4, except the following difference.

In the present embodiment, the light emitting unit further comprises areflecting layer 22, the first semiconductor layer 11 has a bottomsurface 113, the second electrode 16 is disposed on the bottom surface113, and the reflecting layer 22 is disposed on the bottom surface 113without the second electrode 161 formed thereon.

In addition, the reflecting layer 22 is further disposed on a side wall112 of the first semiconductor layer 11, a side wall 121 of the activelayer 12 and a side wall 131 of the second semiconductor layer 13.

Furthermore, the reflecting layer 22 can be served as a distributedBragg reflector (DBR), which can increase the light reflection. Thereflecting layer 22 has a multilayer structure, and therefore a totalreflection can be occurred at the reflecting layer 22. Herein, eachlayer of the multilayer structure can be an insulating layer, such as anoxide film, a nitride film, or an oxynitride film. For example, thematerial for each layer of the multilayer structure can be SiO₂,SiN_(x), SiO_(x)N_(y), TiO₂, Si₃N₄, Al₂O₃, ZrO₂, TiN, AlN, TiAlN, TiSiN,or a combination thereof. However, the present disclosure is not limitedthereto.

The light emitting units disclosed in the aforesaid Embodiments 1 to 5can be applied to a display device. Hereinafter, several examples of thedisplay devices of the present disclosure are illustrated.

Embodiment 6

FIG. 7 is a cross-sectional view of a display device of the presentembodiment. In the present embodiment, the structure shown in FIG. 5 isused, so only the structure differences are illustrated below.

In the present embodiment, the light emitting unit further comprises alight converting layer 23 disposed on the first protecting layer 14.Herein, the light converting layer 23 is also disposed on the secondprotecting layer 21. The light converting layer 23 comprises anencapsulating layer 231 (for example, a surfer-based encapsulatinglayer) and quantum dots 232 dispersed in the encapsulating layer 231.The quantum dots play as light color converting elements.

In addition, in the present embodiment, the display device furthercomprises a base 3, wherein a first pad 31 and a second pad 32 aredisposed on the base 3. Herein, the material for the first pad 31 andthe second pad 32 can be, for example, Ag, Al, Ni, Cr, Cu, Au, Pd, Pt oran alloy thereof, but the present disclosure is not limited thereto.

In the present embodiment, the light emitting unit is disposed on thebase 3, the first electrode 15 electrically connects to the first pad31, the second electrode 16 electrically connects to the second pad 32,and a second encapsulating layer 4 is around a part of the firstelectrode 15, a part of the second electrode 16, the first pad 31 andthe second pad 32. Herein, the second encapsulating layer 4 can besilicon-based encapsulating layer. The material for the silicon-basedencapsulating layer can be, for example, silicon oxide, silicon nitride,silicon oxynitride or a combination thereof, but the present disclosureis not limited thereto.

The encapsulating material for encapsulating the quantum dots 232 is asurfer-based material, which may cause the sulfidation of the firstelectrode 15, the second electrode 16, the first pad 31 and the secondpad 32. Hence, in the present embodiment, when the second encapsulatinglayer 4 is disposed to be around the first electrode 15, the secondelectrode 16, the first pad 31 and the second pad 32, the sulfidation ofthe first electrode 15, the second electrode 16, the first pad 31 andthe second pad 32 can be prevented.

However, in other embodiment of the present disclosure, if the lightconverting layer 23 does not comprise quantum dots but comprisesphosphors or other light color converting materials, the material forencapsulating the phosphors may be or not be the surfer-basedencapsulating.

Embodiment 7

FIG. 8 is a cross-sectional view of a display device of the presentembodiment. The display device of the present embodiment is similar tothat shown in Embodiment 6, except that the light emitting unit furthercomprises a third protecting layer 24 disposed on the light convertinglayer 23. The disposition of the third protecting layer 24 can preventthe deterioration of the quantum dots 232. The material for the thirdprotecting layer 24 can be, for example, silicon oxide, silicon nitride,silicon oxynitride, aluminum oxide, resin, polymer, photoresist, or acombination thereof, but the present disclosure is not limited thereto.

Embodiment 8

FIG. 9 is a cross-sectional view of a light emitting unit of the presentembodiment. In the present embodiment, the structure shown in FIG. 6 isused, so only the structure differences are illustrated below.

In the present embodiment, the light emitting unit further comprises alight converting layer 23 disposed on the first protecting layer 14.Herein, the light converting layer 23 is also disposed on the secondprotecting layer 21. The light converting layer 23 comprises anencapsulating layer 231 (for example, a surfer-based encapsulatinglayer) and quantum dots 232 dispersed in the encapsulating layer 231.

In addition, the light emitting unit further comprises a thirdprotecting layer 24, and the third protecting layer 24 is disposed onthe light converting layer 23 and a side wall 191 of the firstencapsulating layer 19.

Embodiment 9

FIG. 10 is a cross-sectional view of a light emitting unit of thepresent embodiment. The display device of the present embodiment issimilar to that shown in Embodiment 8, except that the light convertinglayer 23 is further disposed between the third protecting layer 24 andthe side wall 191 of the first encapsulating layer 19.

Embodiment 10

FIG. 11 is a cross-sectional view of a light emitting unit of thepresent embodiment. The light emitting unit of the present embodimentcomprises: a first semiconductor layer 11; an active layer 12 disposedon the first semiconductor layer 11; a second semiconductor layer 13disposed on the active layer 12; and a first protecting layer 14disposed on the second semiconductor layer 13. Herein, the firstprotecting layer 14 is further disposed on a side wall 131 of the secondsemiconductor layer 13, a side wall 121 of the active layer 12, and aside wall 112 of the first semiconductor layer 11.

In addition, the light emitting unit further comprises: a firstelectrode 15 and a second electrode 16, the first electrode 15electrically connects to the second semiconductor layer 13, and thesecond electrode 16 electrically connects to the first semiconductorlayer 11. Herein, the first electrode 15 is disposed on the secondsemiconductor layer 13, and the second electrode 16 is disposed underthe first semiconductor layer 11. The first protecting layer 14 isdisposed on a region of the second semiconductor layer 13 without thefirst electrode 15 formed thereon.

Other features of the light emitting unit of the present embodiment aresimilar to those illustrated in the aforementioned embodiments, and notrepeated again.

Embodiment 11

FIG. 12 is a cross-sectional view of a light emitting unit of thepresent embodiment. The light emitting unit of the present embodiment issimilar to that shown in Embodiment 10, except that the light emittingunit of the present embodiment further comprises: a second protectinglayer 21 disposed on the first protecting layer 14. More specifically,all the surfaces of the first protecting layer 14 are covered by thesecond protecting layer 21.

Other features of the light emitting unit of the present embodiment aresimilar to those illustrated in the aforementioned embodiments, and notrepeated again.

The light emitting unit made as described in any of the embodiments ofthe present disclosure as described previously can be applied to variousfields, such as lamps, display devices, or other light source containedin an electronic device.

In addition, the display device made as described in any of theembodiments of the present disclosure as described previously can beco-used with a touch panel to form a touch display device. Meanwhile, adisplay device or touch display device may be applied to any electronicdevices known in the art that need a display screen, such as displays,mobile phones, laptops, video cameras, still cameras, music players,mobile navigators, TV sets, and other electronic devices that displayimages.

Although the present disclosure has been explained in relation to itsembodiment, it is to be understood that many other possiblemodifications and variations can be made without departing from thespirit and scope of the disclosure as hereinafter claimed.

1. A display device, comprising: a light emitting unit, comprising: afirst semiconductor layer; an active layer disposed on the firstsemiconductor layer; a second semiconductor layer disposed on the activelayer; and a first protecting layer disposed on the second semiconductorlayer, wherein the first protecting layer comprises oxygen, nitrogen,and at least one element selected from the group consisting of Al, Ga,In, and Si; wherein, close to the second semiconductor layer, the firstprotecting layer has a first oxygen atomic percentage and a firstnitrogen atomic percentage, and the first oxygen percentage is less thanthe first nitrogen percentage.
 2. (canceled)
 3. The display device ofclaim 1, wherein the first protecting layer has a first top surface, thefirst semiconductor layer has a second top surface, the first topsurface has a first roughness, the second top surface has a secondroughness, and the first roughness is greater than the second roughness.4. The display device of claim 1, wherein the light emitting unitfurther comprises a second protecting layer disposed on the firstprotecting layer, the first protecting layer has a first top surface,the second protecting layer has a third top surface, the first topsurface has a first roughness, the third top surface has a thirdroughness, and the first roughness is greater than the third roughness.5. The display device of claim 1, wherein the light emitting unitfurther comprises a second protecting layer disposed on the firstprotecting layer, the second protecting layer has a second oxygen atomicpercentage, and the first oxygen atomic percentage is less than thesecond oxygen atomic percentage.
 6. The display device of claim 1,wherein the light emitting unit further comprises a second protectinglayer disposed on the first protecting layer, the second protectinglayer has a second nitrogen atomic percentage, and the first nitrogenatomic percentage is less than the second nitrogen atomic percentage. 7.The display device of claim 1, wherein the light emitting unit furthercomprises a first electrode and a second electrode, the first electrodeelectrically connects to the second semiconductor layer, and the secondelectrode electrically connects to the first semiconductor layer.
 8. Thedisplay device of claim 7, wherein the first electrode and the secondelectrode are disposed below the first semiconductor layer, a via holepenetrates through the first semiconductor layer and the active layer,and at least a part of the first electrode is disposed in the via hole.9. The display device of claim 8, wherein a part of the via hole isfurther extended into the second semiconductor layer.
 10. The displaydevice of claim 8, wherein the light emitting unit further comprises apassivation layer, the passivation layer is disposed between the firstelectrode in the via hole and the first semiconductor layer, and thepassivation layer is also disposed on a side wall of the via hole. 11.The display device of claim 7, wherein the light emitting unit furthercomprises a reflecting layer, the first semiconductor layer has a bottomsurface, the second electrode is disposed on the bottom surface, and thereflecting layer is disposed on the bottom surface without the secondelectrode formed thereon.
 12. The display device of claim 11, whereinthe reflecting layer is further disposed on side walls of the firstsemiconductor layer, the active layer and the second semiconductorlayer.
 13. The display device of claim 11, wherein the reflecting layerhas a multilayer structure, and each layer of the multilayer structureis an oxide film, a nitride film, an oxynitride film, or a combinationthereof.
 14. The display device of claim 7, wherein the light emittingunit further comprises a light converting layer disposed on the firstprotecting layer, and the light converting layer comprises aencapsulating layer and quantum dots dispersed in the encapsulatinglayer.
 15. The display device of claim 14, wherein the light emittingunit further comprises a third protecting layer disposed on the lightconverting layer.
 16. The display device of claim 14, wherein the lightemitting unit further comprises a first encapsulating layer, the firstencapsulating layer is around a part of the first electrode and a partof the second electrode, and the first encapsulating layer is disposedon side walls of the first semiconductor layer, the active layer and thesecond semiconductor layer.
 17. The display device of claim 16, whereinthe light emitting unit further comprises a third protecting layer, andthe third protecting layer is disposed on the light converting layer anda side wall of the first encapsulating layer.
 18. The display device ofclaim 17, wherein the light converting layer is disposed between thethird protecting layer and the side wall of the first encapsulatinglayer.
 19. The display device of claim 14, further comprises a base,wherein a first pad and a second pad are disposed on the base, the lightemitting unit is disposed on the base, the first electrode electricallyconnects to the first pad, the second electrode electrically connects tothe second pad, and a second encapsulating layer is around a part of thefirst electrode, a part of the second electrode, the first pad and thesecond pad.
 20. A light emitting unit, comprising: a first semiconductorlayer; an active layer disposed on the first semiconductor layer; asecond semiconductor layer disposed on the active layer; and a firstprotecting layer disposed on the second semiconductor layer, wherein thefirst protecting layer comprises oxygen, nitrogen, and at least oneelement selected from the group consisting of Al, Ga, In, and Si;wherein, close to the second semiconductor layer, the first protectinglayer has a first oxygen atomic percentage and a first nitrogen atomicpercentage, and the first oxygen percentage is less than the firstnitrogen percentage.